1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a perpendicular magnetic recording head and a method of manufacturing the same, and more particularly, to a perpendicular magnetic recording head having an improved high frequency characteristic by reducing the inductance thereof, and a method of manufacturing the same.
2. Description of the Related Art
Magnetic recording methods can be classified into longitudinal magnetic recording methods and perpendicular magnetic recording methods. In a longitudinal magnetic recording method, information is recorded based on the magnetization direction of a magnetic layer that is parallel to a surface of the magnetic layer, and in a perpendicular magnetic recording method, information is recorded based on the magnetization direction of a magnetic layer that is perpendicular to the surface of the magnetic layer. In terms of recording density, the perpendicular magnetic recording method is superior to the longitudinal magnetic recording method, and thus, various perpendicular magnetic recording heads have been developed.
FIG. 1 is a cross-sectional view of a related art perpendicular magnetic recording head 10. Referring to FIG. 1, the related art perpendicular magnetic recording head 10 includes a recording head unit that includes a main pole 22, a return yoke 24, a sub-yoke 28, and a coil 26 and a read head unit that includes two magnetic shield layers 30 and a magnetic resistance device 15 interposed between the two magnetic shield layers 30. The coil 26 surrounds the main pole 22 and the sub-yoke 28 in a solenoid shape, and when a current is applied to the coil 26, the main pole 22, the sub-yoke 28, and the return yoke 24 form a magnetic path of the magnetic field. The magnetic path that proceeds towards a recording medium (not shown) from the main pole 22 magnetizes a recording layer of the recording medium in a perpendicular direction and returns to the return yoke 24 and thus, recording is performed. The magnetic resistance device 15 can read information recorded in the recording medium by the characteristics of changing electrical resistance by a magnetic signal generated from the magnetization of the recording layer.
In the perpendicular magnetic recording head 10, the return yoke 24 is formed according to the shape of an insulating layer 27 that covers the coil 26. The shape of the insulating layer 27 is naturally formed in a process of spin coating a photoresist for covering the entire coil 26 and hard baking the photoresist. The length L and height H of the insulating layer 27 formed between the return yoke 24 and the main pole 22 directly affect the shape of the return yoke 24, and also determines the total length of the magnetic path. The length of the magnetic path directly affects the inductance of the perpendicular magnetic recording head 10, and the longer the magnetic path is, the higher the inductance is. Also, to increase the recording density, a high frequency current is applied to the coil 26. However, since the main pole 22, the return yoke 24, and the sub-yoke 28 are generally formed of a magnetic material having electrical conductivity, an eddy current is generated at high frequency. The eddy current causes a further increase in the inductance at high frequency. Accordingly, the inductance increases a rise time of a magnetic field with respect to a current, that is, the inductance generates an interval between the time when a current is applied to the coil 26 and the time when the recording magnetic field is formed in the main pole 22. The time interval causes thermal noise, and thus, reduces the high frequency characteristics of the perpendicular magnetic recording head 10. Therefore, it is needed to design a perpendicular magnetic recording head having reduced inductance in order to achieve high density recording.